Ca2+, redox, and thermoresponsive supramolecular hydrogel with programmed quadruple shape memory effect

A new shape memory hydrogel, which can be programmed with quadruple geometries when stimuli are applied sequentially, is presented. With a new redox-responsive stimulus coupled with two other common regulation mechanisms, this hydrogel shows multiple shape memory behaviours, which is promising for various applications, especially drug delivery.